There is a difference between משכן (Tabernacle) and אהל מועד (Tent of Meeting): משכן comes with respect to its structure, that it is made to be carried and to be a dwelling place in its time of resting. And the noun אהל מועד refers to its purpose, that it is designated for the Divine Presence there.

And thus, the noun משכן is used in any place where it speaks about its structure or about journeys, while the noun אהל מועד is used in any place where it speaks about the services and the sacrifices.